I enjoy cycling, mainly on the road, and some mountain biking however I have reservations about the use of mountain bikes on footpaths (there’s a clue in the name) in the mountains.
I encountered mountain bike riders on the TMB and my reservations were towards were reinforced. “Fragile” ground e.g. soft ground or areas covered in alpine plants is rapidly damaged by the passage of just a few mountain bikes. Their passage is immediately obvious on the ground; groooves cut into the ground providing channels for water and subsequent erosion. Yes, the passage of walkers also causes erosion however not at the same rate. Studies have been carried out although the objectivity of some must be called into question. Alpine vegetation, especially above 1800m has a hard time surviving with a very short growing season). Any damage will take a long time to recover; if indeed it ever does.
Conflict with other, existing, users is also an issue. I had walked past a substantial flock of sheep climbing to the Col de la Seigne. A small group of mountain bikers road at high speed through the herd of sheep scattering them across the hillside. The shepherd was understandably upset, shouting at them.
The same mountain bikers then headed down the path towards me. I stayed on the path. The traditional etiquette in the mountains is that those descending give way to those coming up; as clearly it’s more of an effort. The expectation of the mountain was that I would “jump” out of the way. Sadly it appears that the mentality of (at least some) is similar to that of car drivers with cyclists – might is right.
It’s interesting to read that there’s a “Mountain Bikers Charter” that clearly states that pedestrians have priority and to pass slowly or even get off. I chatted with a French Accompagnatrice from the Chamonix Guides bureau (who was on her 12th Tour du Mont Blanc of the year) and I was pleased that she was entirely in agreement over incompatibility of mountain biking on the TMB.
I don’t believe that mountain bikes in the mountains is a sustainable activity apart from on prepared and designated trails. The Vanoise National Park already forbids mountain biking apart from on a few name tracks. Why? The Park feels that mountain biking and the peaceful enjoyment of the park by walkers is not comptable. I happen to think they are right.